Verifiers, as the term is used herein, are devices that are used to measure encoded indicia and to provide qualitative and/or quantitative analysis of the suitability of the encoded indicia for particular applications, i.e., a measurement of the quality of the encoded indicium, or qualification of the encoded indicium. Verifiers used to examine encoded indicia comprising one-dimensional (1D) and two-dimensional (2D) bar codes, optically recognized characters, and other optically observable symbols are well known. Optical verifiers described in the patent literature for examining encoded indicia include those that use laser scanners, those that use linear arrays of optical detectors such as charge-coupled devices (CCDs), and those that use two-dimensional arrays of optical detectors, such as CCD arrays and vidicons. In general, the verifiers that have been described in the literature are reported to be useful in the analysis of the quality of encoded indicia over the widest possible range of conditions, including operation at arbitrary and variable distances, operation under a variety of ambient illuminating conditions, and operation using moving encoded indicia as targets for qualification.
Certain standards for qualifying various encoded indicia have been available for some time, such as American National Standards Institute (ANSI) Specification “Bar Code Print Quality Guideline” X3.182-1990 and the “UPC Symbol Specification Manual” and “Quality Specification for the UPC Printed Symbol”, published by the Uniform Code Council, Inc., Dayton, Ohio 1993. The ANSI specifications assign a letter grade, “A” through “F”, to the encoded indicium based on the lowest letter grade obtained on several different test parameters.
The prior art verifier systems suffer from various problems. For example, one prior art system requires the user to calibrate the verifier before each usage, in order to determine a working distance and orientation to a target encoded indicium. The calibration procedure requires at least one calibration standard, and may require multiple calibration standards. In some prior art systems, the user must configure the imaging system to obtain a spot size at the target encoded indicium according to the requirements of the ANSI specification. Some prior art systems require the user to manually orient the imager (or an extension thereof) used to obtain an image of the target encoded indicium so that a plurality of switches or contact indicators are simultaneously activated before the verifier can operate. Other prior art systems require the user to confirm visually that the imager is correctly aligned with the target encoded indicium.
There is a need for a verifier that is simple and convenient to operate, but that overcomes all of the shortcomings of the prior art.